1. Field
The following description relates generally to communications systems, and more particularly to ordering of registration messages to access points that are in a communication with a mobile device.
2. Background
Communication networks, such as wireless communication networks, broadband networks, and other suitable networks are utilized in connection with transferring data, wherein data can include word processing files, streaming video, multimedia files, voice data, and/or the like. Such networks are often employed with protocols such as Internet Protocol (IP) for transferring data in accordance with a public network such as the Internet. An extension of IP protocols relates to mobile devices and is known as Mobile Internet Protocol (MIP). Another variant is Proxy Mobile Internet Protocol (PMIP). Such mobile protocols are often employed with a network domain that includes nodes such as access nodes and Local Mobility Anchors (LMA) for example that often employ the mobile IP protocols in conjunction with a domain protocol to manage the respective devices within the domain.
One such domain protocol is referred to as a Network-based Localized Mobility Management (NETLMM) protocol. In contrast to MIP protocol which is considered a global mobility management protocol to control IP links as communications devices change location, NETLMM and PMIP help localize the management of topologically small device movements. Limiting the reach of the respective protocol responsibilities is more preferable to handle local movements since protocol complexities are reduced. Generally, NETLMM provides for efficient support for mobile nodes communicating with peers both outside and inside the same mobility domain when mobile nodes move across different access routers (or nodes, or points). These movements typically require no extra host stack support or complex security and signaling interactions between mobile node and the respective access network. By utilizing the neighbor access router information in the domain, NETLMM can achieve very fast and smooth handover performance to suit the requirements of most real-time and interactive multimedia applications.
Network based mobility management systems employing technologies such as NETLMM, PMIP are generally considered mobility management systems that do not require mobility management signaling from a mobile device to operate. Instead, the network or domain changes message routing within the network based on link layer or other triggers. A well understood limitation of such mechanisms is that they can only operate with mobiles that maintain a single link to the network. In other words the mobility management system points to a single point of attachment for each mobile. Since the mobile is assumed to have only one link with an NETLMM domain for example, at any one time the NETLMM protocol must ensure that the local mobility anchor (LMA) redirects the mobile device's traffic to the correct access router i.e., the access router the mobile is connected to. To perform this operation, access routers send registration messages to the LMA when a mobile device creates a link with the LMA. Assuming the mobile device can only have one link at the time, the order in which the registration messages reach the LMA is assumed to be the same as the order in which the mobile device creates links with different access routers. This assumption can hold if the movement between access routers is not very frequent. More specifically, the assumption holds when the time between link creations is larger than the time it takes for the access router to register with the LMA.
Referring to prior art FIG. 10, an example domain 1000 is illustrated. The domain 1000 includes an LMA 1010 that communicates with access nodes (AN) (or routers) 1020 and 1030. The AN's 1020,1030 communicate with access point (AP) groups 1040 and 1050 respectively, where such groups may service a mobile device 1060. The mobile device 1060 maintains a link with Access Point 2 (AP2) 1070, which is directly connected to the AN at 1020. In this example, NETLMM protocol schemes work relatively well since only movement between ANs 1020 and 1030 is triggering NETLMM device registrations, while movement between APs at 1040 or 1050 under the same AN 1020 or 1030 do not trigger such registrations. Even in this case, however, movement between AP2 at 1070 and AP4 at 1080 can cause out of order delivery of the registrations to the LMA 1010, if for example the mobile device moves too fast or if it moves back and forth between AP2 1070 and AP4 1080, a condition commonly referred to as “ping-pong.” As can be appreciated, back and forth movements can cause communications problems within the domain 1000.